Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. Translation began only after the appearance of written literature; there exist partial translations of the Sumerian Epic of Gilgamesh (ca. 2000 BCE) into Southwest Asian languages of the second millennium BCE.
As is apparent to anyone who has read a translation from a source natural language (e.g., English, Spanish, etc.) into a destination natural language, it is very difficult, even for multi-lingual humans, to produce a translation that is faithful in meaning to the original source text. Computer-generated translations typically fall short of those produced by skilled humans, as evidenced by the fact that text translated from one language to another by a computer, and then translated back to the original language by the computer, often differs greatly in meaning from the original text. A well-known example from the early days of computer-based translation is a translation of the English sentence “The spirit is willing, but the flesh is weak” into Russian, and then back from Russian to English, with the result in English being “The vodka is good, but the meat is rotten.” Another well-known example illustrating the difficulties of translation is the English sentence “Time flies like an arrow, but fruit flies like a banana.”